Effects of intravenous anesthetics on normal and passively sensitized human isolated airway smooth muscle.
BACKGROUND
General anesthetics may modify airway responsiveness. The authors investigated the effect of thiopental, propofol, and etomidate on airway smooth muscle.


METHODS
Contraction experiments were done in human airway rings that were either normal or passively sensitized with asthmatic serum. The effect of propofol and etomidate was also studied on both [Ca2+]i increase measured by microspectrofluorimetry in isolated myocytes and isometric contraction in the rat trachea.


RESULTS
In human bronchi, thiopental (10[-7] to 10[-4] M) induced a concentration-dependent contraction. Neither propofol nor etomidate altered baseline tone, but both anesthetics reduced histamine-induced contraction. In human immunologically sensitized isolated bronchi, propofol (3 x 10[-4] M) reduced histamine reactivity (deltaFmax in %) to a greater degree than in nonsensitized tissues (64.4 +/- 15.7% and 16.4 +/- 8.5%, respectively; n = 6, P < 0.05), whereas the effect of etomidate (10[-4] M) was similar in both types of tissue (24.1 +/- 6% and 22.3 +/- 15%, respectively, n = 6). In rat isolated tracheal myocytes, propofol (3 x 10[-4] M) and etomidate (10[-4] M) altered the [Ca2+]i signal in response to the depolarizing agent potassium chloride and the muscarinic agonist acetylcholine. Accordingly, the two anesthetics also reduced the mechanical response of rat tracheal rings to these agonists.


CONCLUSIONS
Whereas thiopental contracts human isolated bronchi, propofol and etomidate reduce histamine-induced contraction in human isolated airway smooth muscle that were either not sensitized or passively sensitized with asthmatic serum. This effect involves inhibition of both electro- and pharmacomechanical coupling.
Ouedraogo
N
N
Laboratoire de Physiologie Cellulaire Respiratoire, Université Victor Ségalen-Bordeaux 2, France.
Roux
E
E
Forestier
F
F
Rossetti
M
M
Savineau
J P
JP
Marthan
R
R
D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001980:Bronchi / Q000187:drug effects*; D004347:Drug Interactions; D005045:Etomidate / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D006801:Humans; D007114:Immunization; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013874:Thiopental / Q000494:pharmacology; D014132:Trachea / Q000187:drug effects
D018686:Anesthetics, Intravenous; D006633:Histamine Antagonists; D013874:Thiopental; D015742:Propofol; D005045:Etomidate